Supporting information Improved synthesis of the super

Supporting information

1


Improved synthesis of the super antioxidant, ergothioneine and its

biosynthetic pathway intermediates.

Peguy Lutete Khonde and Anwar Jardine*

Department of Chemistry, Faculty of Science, University of Cape Town, South Africa

*Corresponding Author: [email protected]

Table of Contents

S1. Synthesis and Characterisation of Compounds ................................................................... 2

S1.1. General Procedures .................................................................................................................... 2

S1.2. Synthesis and characterisation of Compounds. ......................................................................... 4

S1.3. 3 D ChemBioDraw Ultra 11.0 modelling of mCPBA oxidation of sulfide (3a) to sulfoxide

(4b) (milder oxidation) ...................................................................................................................... 10

S1.4. Evidence of diastereoselectivity of sulfoxidation revealed by 1H NMR spectrum of S-(β-

amino-β-carboxyethyl)ergothioneine methyl ester sulfoxide (4b) .................................................... 10

S1.5. Synthesis of hercynine and ergothioneine deuterated compounds .......................................... 14

S1.6. Characterisation of Mercaptohistidine (8) synthesized ............................................................ 16

S1.7. 1H NMR of ergothioneine-d3 (10) synthesized ........................................................................ 18

S1.8. Synthesis of Ergothioneine substrates and inhibitor ................................................................ 18

S1.9. Selective and mild bromination of the imidazole ring ............................................................. 24

S1.10. Hercynyl cysteine thioether (15) (One pot synthesis) ............................................................ 25

S1.11. Synthesis of hercynyl cysteine sulfoxide (I) and sulfone (II). ............................................... 26

S2. Total Protein extraction and Purification from Mycobacterium smegmatis. ..................... 28

S2.1. Mc2155 (M. smegmatis) growth conditions. ............................................................................ 28

S2.2.Total protein extraction. ............................................................................................................ 28

Electronic Supplementary Material (ESI) for Organic & Biomolecular Chemistry.This journal is © The Royal Society of Chemistry 2014

mailto:[email protected]


2

S2.3. Total protein purification. ........................................................................................................ 29

S2.4. Protein calibration curve .......................................................................................................... 29

S3. HPLC –ESI/MS (QTOF) analysis. .................................................................................... 29

S3.1. Materials and methods ............................................................................................................. 29

S3.2. Experimental LCMS ................................................................................................................ 30

S4. In vitro reconstituted biosynthesis of ergothioneine in Mycobacteria smegmatis ............ 34

S4.1. ESH Calibration curve ............................................................................................................. 35

S4.2. Enzymatic synthesis of ergothioneine-d3 (10) using Hercynine-d3 (7) as a substrate. ............ 36

S4.3. Biotransformation of substrates to ergothioneine using crude M. smegmatis enzymes

preparation ........................................................................................................................................ 36

S4.4. Non enzymatic cleavage of C-S bond catalysed by PLP ......................................................... 37

S5. Proposed mechanism of reaction of C-S of sulfide (15), sulfoxide (II) and sulfone (III)

catalysed by PLP. ..................................................................................................................... 39

S6. References.......................................................................................................................... 40

S1. Synthesis and Characterisation of Compounds

S1.1. General Procedures

All solvents were dried by appropriate techniques and freshly distilled before use. All

commercially available reagents were purchased from Sigma-Aldrich and Merck and were

used without further purification.

Unless otherwise stated, reactions were performed under an inert atmosphere of nitrogen in

oven dried glassware and monitored by thin-layer chromatography (TLC) carried out on Merck

silica gel 60-F254 sheets (0.2 mm layer) pre-coated plates and products visualized under UV

light at 254 nm or by spraying the plate with an ethanolic solution of ninhydrin (2% v/v)

followed by heating.

Column chromatography was effected by using Merck Kieselgel silica gel 60 (0.040-0.063

mm) and eluted with an appropriate solvent mixtures. All compounds were dried under vacuum

before yields were determined.


3

Nuclear magnetic resonance spectra (1H and 13C) were recorded on a Varian Mercury 300 MHz

(75 MHz for 13C), Varian Unity 400 MHz (101 MHz for 13C), a Bruker unity 400 MHz (101

MHz for 13C), or a Bruker unity 600 MHz (151 MHz for 13C) and were carried out in CDCl3,

DMSO-d6 and D2O as the solvent unless otherwise stated. Chemical shifts are given in ppm

relative to tetramethylsilane (TMS, δ = 0.00 ppm), which is used as internal standard.

Assignments were confirmed by COSY, APT and HSQC analysis, when required. Coupling

constants (J) are reported in Hertz (Hz). The spin multiplicities are indicated by the symbol s

(singlet), d (doublet), dd (doublet of doublets), t (triplet), m (multiplet), q (quartet) and br

(broad).

Optical rotations were obtained using a Perking Elmer 141 polarimeter at 20°C. The

concentration c refers to g/100ml.

Melting points were determined using a Reichert-Jung Thermovar hot-plate microscope and

are uncorrected. Infra-Red spectra were recorded on a Perkin-Elmer FT-IR spectrometer (in

cm-1) from 4000 cm-1 to 450 cm-1.

Mass spectra were recorded on a JEOL GC MATE ΙΙ magnetic sector mass spectrometer and

the base peaks are given, University of Cape Town.

LCMS analyses were carried out with a UHPLC Agilent 1290 Infinity Series (Germany),

accurate mass spectrometer Agilent 6530 Quadrupole Time Of Flight (QTOF) equipped with

an Agilent jet stream ionization source (positive ionization mode) (ESI+) and column (Eclipse

+ C18 RRHD 1.8 µm.2.1 X 50, Agilent, Germany).

Enzymatic reactions were allowed to incubate in Nuaire incubator (DH Autoflow CO2 Air –

jarcketed Incubator), and centrifuged in Eppendhorf centrifuge (Model 5810R, Germany),

Tygerberg Stellenbosch University, Cape Town, South Africa.


4

S1.2. Synthesis and characterisation of Compounds.

NHN

HN

O

OS

NHR2

Cl

O

OR1

(i)

R1 = -CH3 or allyl

R2 = BocErgothioneine (1)

NHN

N

O

OR3S

R2HN

R1O2C2a - 2cNHN

N

O

OR3S

R2HN

R1O2CO

(ii)3a : R1=Me, R2=Boc, R3=H3b : R1=Me, R2=R3=H3c : R1=Allyl, R2=Boc, R3=H

5a : R1=R2=R3=H

5b : R1=Bn, R2=Boc, R3=Bn

(iii)

(v) (vi)

4a : R1=Me, R2=Boc, R3=H

4b : R1=Me, R2=R3=H(iv)

(iv)

X

NHN

N

O

OS

H2N

HO2CO

II

aq acid, base or esterase

Scheme S1. 2. 1. Synthesis of ergothioneine sulfoxide protected (4a, 4b). Reagents and conditions: (i) Et3N

/ H2O 5 h at 30°C, (3a); (ii) N-Boc deprotection: TFA, DCM / H2O, 0-5°C (3b), (4b) or (II) (iii) a) RhCl(PPh3)3,

EtOH/ H2O (1:1) reflux b) TFA, DCM / H2O, 0-5°C (5a); (iv) mCPBA, H2O / DCM 1:1, 5 hr at 25°C (4a).

L-hercynine or (2S)-N,N,N-2-trimethylethanaminium-3-(1H-imidazol-4-yl)propanoic

acid 1

N

23

4'

5'HN

2'N

O

O

1'' 3''

1

1'

3'

2''

N,N,-dimethyl L-histidine (6) (653 mg; 3.56 mmol) was dissolved in methanol (20 ml), and the

pH was adjusted to 8-9 with a concentrated solution of NH4OH (25 %, 80 µl), followed by the

addition of methyl iodide (700 mg; 4.93 mmol). The resultant solution was allowed to stir at

room temperature for 24 hours. The solvent was evaporated to dryness to afford a crude product

L- hercynine which was recrystallized in a mixture of warm methanol and diethyl ether to yield

hydroiodide salt form of L-hercynine as a white solid (489 mg; 42 %). Mp: 240-242°C (with

decomposition); νmax KBr /cm-1 3435s (N-H) 1632m (RCOOH) 1496 w (C=C Aromatic)

1335w (C-N); [α]20D = +48.7° (c = 0.9, 5 N HCl); 1H NMR (400 MHz, D2O) δ 8.76 (s, 1H, H-

2'), 7.51 (d, J = 12.7 Hz, 1H, H-5'), 4.02 – 3.83 (m, 1H, H-2), 3.49 (s, 9H, H-1''H-2''H-3''), 3.12

(dd, J = 12.7, 4.1 Hz, 1H, H-3a) 3.06 (dd, J = 12.7, 4.1 Hz, 1H, H-3b); 13C NMR (101 MHz,

D2O)δ 166.8 (C-1), 135.5 (C-2'), 134.3 (C-5'), 118.3 (C-4'), 72.7 (C-2), 53.0 (C-1''C-2''C-3''),

22.3 (C-3); LRMS (EI+) m/z calculated for C9H17N3NaO2+ 223.1 found 223.6 ([M+H+Na]+;

20.4%).


5

Hercynine synthesis (one pot) 2

L-histidine (293 mg; 1.6 mmol) was dissolved in NaOH (10 %, 4 ml) followed by the addition

of Me2SO4 (0.4 ml; 532 mg; 4.2 mmol). The reaction was allowed to stir for 30 min at 0°C and

for further 30 min at room temperature. The solution was neutralized with 0.5 N HCl, and

lyophilised to dryness. The residue was triturated with Et2O, to yield the L-hercynine as white

solid (300 mg), which was used without further purification.

Ergothioneine (1), or (2S)-N,N,N-2-trimethylethanaminium (2-mercapto-1H-imidazol-4-

yl) propanoic acid (1).

N

23

4'

5'HN

2'

HN

O

O

1'' 3''

1

1'

3'

2''

S

The synthesis of Ergothioneine (1) was carried out as reported by Trampota et al.3

107 mg of L-(+)-ergothioneine (1) was synthesized. Mp:276-279 °C literature 275-277°C 3;

[α]20D = +138.21° (c = 1; H2O)3; Rf silica gel 0.3 (methanol/water 9:1); 1H NMR (400 MHz,

D2O) δ 7.05 (m, 1H, H-5’), 3.76 (dd, J = 11.7, 4.0 Hz, 1H, H-2), 2.88 (m, 2H, H-3), 2.75 (s,

9H, NMe3); 13C NMR (101 MHz, D2O)δ 177.0 (C-1), 161.2 (C-2'), 128.9 (C-4'), 103.4 (C-5'),

60.6 (C-2), 55.6 (NMe3), 24.9 (C-3); νmax (KBr)/cm-1 3138s (NH) 1746s (RCOOH), 1995m

(N=C-S), 1403s (C=C aromatic ring); HRMS (ESI+): m/z 230.0963 [M]+. Calculated for

C9H16N3O2S+, found 230.0958 [M]+.

(S)-Methyl 2-(tert-butoxycarbonylamino)-3-chloropropanoate (2a) 4

2, 4, 6-Trichloro-[1, 3, 5] triazine (1.87 g; 10.1 mmol) was added portion wise in DMF (2ml)

at an internal temperature was maintained at 25 °C. After the formation of a white solid, the

reaction was monitored (TLC) until complete disappearance of TCT, thereafter CH2Cl2 (25 ml)

was added, followed by the addition of N-Boc L-serine methyl ester (2.22 g; 10.1 mmol). The

resultant mixture was allowed to stir at room temperature, monitored (TLC pet-ether: EtOAc,

1:1) until completion (ca 4 h). The reaction mixture was diluted with water (20 ml) and washed

with saturated aqueous sodium carbonate solution (2 × 15 ml) followed by 1 N HCl and brine.


6

The combined organic phases were dried (Na2SO4), filtered and concentrated under vacuum.

The residue was purified by flash column chromatography (petroleum ether: EtOAc 1:1) and

was crystallized and recrystallized in a mixture of petroleum ether (40-60°C) and ethyl acetate

to afford (S)-methyl 2-(tert-butoxycarbonylamino)-3-chloropropanoate (2a) as a white solid

(736 mg; 31 %). Mp: 59-61 °C; νmax (KBr) / cm-1 3362s (NH) 2991s + 2943s (C-H, aliphatic)

1739s 1294s (RCOOMe) 809s + 852m (C-Cl); [α]20D = +32.5° (c = 0.15; CHCl3) Lit [α]20

D =

+37.8° (c = 0.15; CHCl3)5; 1H NMR (300 MHz, CDCl3) δ 5.43 (s, 1H, NH), 4.69 (br.s, 1H, H-

2), 3.96 (dd, J = 4.6 Hz, 3.4 Hz, 1H, H-3a), 3.84 (dd, J = 4.6 Hz, 3.4 Hz, 1H, H-3b), 3.80 (s;

3H, OCH3), 1.46 (s, 9H, Boc); LRMS (EI)+ m/z calculated for C9H15Cl35NO4 236.1 found 235.8

([35M-H]+; 5.3 %), 138.0 ([35M+- Boc ]; 11 %), 140.0 ([37M+- Boc ]; 2.6 %).

(S)-allyl 2-(tert-butoxycarbonylamino)-3-chloropropanoate (2c) 6

2, 4, 6-Trichloro-[1, 3, 5] triazine (577 mg; 3.13 mmol) was added portion wise in DMF (1ml)

at an internal temperature was maintained at 25 °C. After the formation of a white solid, the

reaction was monitored (TLC) until complete disappearance of TCT, thereafter CH2Cl2 (20 ml)

was added, followed by the addition of N-Boc L-serine allyl ester (768 mg; 3.13 mmol). The

resultant mixture was allowed to stir at room temperature, monitored (TLC pet-ether: EtOAc,

2:1) until completion (ca 10 h) The reaction mixture was diluted with water (20 ml) and washed

with saturated aqueous sodium carbonate solution (2 × 15 ml) followed by 1 N HCl and brine.

The combined organic phases were dried (Na2SO4), filtered and concentrated under vacuum.

The residue was purified by flash column chromatography (petroleum ether: EtOAc 2:1) to

afford (S)-allyl 2-(tert-butoxycarbonylamino)-3-chloropropanoate (2c) as a yellow oil (729

mg; 2.76 mmol; 89 %); [α]20D = +23.94° (c = 0.35, CH2Cl2); Rf 0.75 (hexane/EtOAc 2: 1); 1H

NMR (400 MHz, CDCl3) δ 5.91 – 5.75 (m, 1H, H-2'), 5.37 (brs, 1H, NH), 5.27 – 5.12 (m, 2H,

H-3'), 4.52 - 4.45 (m, 2H, H-1') 4.39 - 4.30 (m, 1H, H-2), 3.96 (dd, J = 8.1, 3.8 Hz, 1H, H-3a),

3.91 (dd, J = 8.1, 3.8 Hz, 1H, H-3b), 1.45 (s, 9H, Boc); 13C NMR (101 MHz, CDCl3)δ 171.3

(C-1), 154.3 (C=O Boc), 114.1 (C-2'), 72.4 (C-3'), 70.1 (C(Boc)), 63.7 (C-2), 52.7 (C-1'), 30.5

(C-3), 28.4 (3C, (Boc)); LRMS (EI+) m/z calculated for C6H8ClNO2 161.0 for Cl35 and 162.0

for Cl37 found 160.1 ([M Cl35-Boc - H]+; 30 %), 162.1 ([M Cl37-Boc - H]+, 10 %); 133.0 ([M

Cl35 - Boc – CH2=CH2 - H]+; 100 %).


7

(2S)-N,N,N-2-trimethylammonium-3-[2-((2R)-2-(tert-butoxycarbonylamino)-3-

methoxycarbonyl)- ethylthio)-1H-imidazol-4-yl)] propanoic acid (3a) 7

N

23

5'HN

N

O

OS

1''

2''

BocHN

13''

4'

3'

1'

2'OO

2'''

3'''1'''

N-Boc-β-chloro-L-alanine methyl ester (2a) (93 mg; 0.39 mmol) was dissolved in a mixture of

DCM: H2O (50:50; 4 ml) followed by the addition of Et3N (0.4 mL) which adjusted the pH of

the solution to 9-10. The resulting mixture was allowed to stir at room temperature for 30 min

and subsequently followed by the addition of ergothioneine (1) (89 mg; 0.34 mmol). The

solution was allowed to stir at 30 °C for 5 hours. The solvent was removed under high vacuum

to dryness and the crude product was purified by reverse chromatography (C18) to afford (2S)-

N,N,N-2-trimethylammonium-3-[2-((2R)-2-(tert-butoxycarbonylamino)-3-methoxycarbonyl)-

ethylthio)-1H-imidazol-4-yl)] propanoic acid (3a) as a pale yellow solid (92 mg; 0.20 mmol;

51 %); 1H NMR (400 MHz, D2O) δ 5.95 (s, 1H, H-5'), 4.51 - 4.43 (m, 1H, H-2), 4.27 - 4.19 (m,

2H, H-1''), 4.10 (dd, J = 10.0, 4.0 Hz, 1H, H-3a) 4.05 (dd, J = 10.0, 4.0 Hz, 1H, H-3b), 3.36 -

3.25 (m, 1H, H-2''), 2.49 (s, 3H, OCH3), 1.59 (s, 9H, H-1''' H-2''' H-3'''), 1.56 (s, 9H, Boc);

LRMS m/z calculated for C18H31N4O6S+ 431.2 found 431.8 ([M+]; 2.5 %).


allyloxycarbonyl)- ethylthio)-1H-imidazol-4-yl)] propanoic acid (3c) 7

N

23

5'NH

N

O

O

S

1''

2''

BocHN

1

3''

4'3'

1'

2'O

O

2'''

3'''

1'''

N-Boc-β-chloro-L-alanine allyl ester (2c) (728 mg; 2.76 mmol) was dissolved in a mixture of

THF:H2O (66:34; 15 ml) followed by the addition of Et3N (0.5 ml) which adjusted the pH of

the solution to 9-10. The solution was allowed to stir at room temperature for 30 min and

subsequently followed by the addition of ergothioneine (1) (729 mg, 2.76 mmol). The solution

was allowed to stir at 30 °C for 5 hours. The solvent was removed under high vacuum to

dryness and the crude product was purified by reverse chromatography (C18) to afford (2S)-


8

N,N,N-2-trimethylammonium-3-[2-((2R)-2-(tert-butoxycarbonylamino)-3-allyloxycarbonyl)-

ethylthio)-1H-imidazol-4-yl)] propanoic acid (3c) as yellow hygroscopic solid (1.12 g; 2.27

mmol; 82 %). Mp: 195-197 °C; νmax (CH2Cl2)/cm-1) 3350m (NH) 1732s + 1163s + 1046

(RCOOR) 895s (N=C-S); 1H NMR (300 MHz, DMSO) δ 6.88 (brs, 1H, H-5'), 5.98 – 5.80 (m,

1H, H-2'''), 5.32 (dd, J = 10.3 ,1.5 Hz, 1H, H-3'''a), 5.20 (dd, J = 10.3, 1.5 Hz, 1H, H-3'''b), 4.95

(m, 1H, H-2''), 4.58 (t, J = 7.8 Hz, 1H, H-2), 4.07 (m, 2H, H-1''), 3.66 (t, J = 4.8 Hz, 2H, H-

1'''), 3.05 (s, 9H, NMe), 2.98 (m, 2H, H-3), 1.38 (s, 9H, Boc); 13C NMR (101 MHz, DMSO) δ

171.1 (C-3''), 155.7 (C-1, C=O(Boc)), 132.8 (C-2', C-3'''), 117.7 (C-2''', C-4') 111.4 (C-5'), 78.7

(C-2), 65.0 (C(Boc)), 61.6 (C-1'''), 56.8 (C-2''), 45.8 (C-1''), 44.2 (NMe3), 28.5 (3C(Boc)), 18.9

(C-3).


methoxycarbonyl)- ethylsulfinyl)-1H-imidazol-4-yl)] propanoic acid (4a)

N

23

5'NH

N

O

O

S

1''

2''

BocHN

1

3''

4'3'

1'

2'O

O O

(2S)-N,N,N-2-trimethylammonium-3-[2-((2R)-2-(tert-butoxycarbonylamino)-3

methoxycarbonyl)-ethylthio)-1H-imidazol-4-yl)] propanoic acid (3a) was dissolved in a

mixture of H2O: DCM (50:50; 4 ml) followed by the addition of mCPBA (13 mg; 0.06 mmol;

77 %). The solution was allowed to stir at 0-5°C for 3-5 hours until completion (TLC). The

solution was partitioned in a separator funnel, water layer was returned and organic layer

discarded. Water layer was treated with amberlyst (H+ form) to neutral and then extracted with

DCM to remove any organic impurities. Water layer was returned and lyophilised to dryness.

The residue was purified by reverse phase chromatography (C18) to afford (2S)-N,N,N-2-

trimethylammonium-3-[2-((2R)-2-(tert-butoxycarbonylamino)-3-methoxycarbonyl)-

ethylsulfinyl)-1H-imidazol-4-yl)] propanoic acid (4a) as a pale yellow crystal (25 mg; 0.06

mmol; 96 %). 1H NMR (400 MHz, D2O) δ 6.10 (s, 1H, H-5’) 4.07 (brs., 1H, H-2) 3.89 (m, 2H,

H-3) 3.77 (s, 3H, OCH3) 3.72 -3.67 (m, 1H, H-2'') 3.60 (dd, J = 11.72, 6.41 Hz, 1H, H-1''a)

3.42 (dd, J = 11.72, 6.41 Hz, 1H, H-1''b) 2.98 (s, 9H, NMe3) 1.47 (s, 9H, Boc); MS (EI+) m/z

calculated C18H31N4O7S+ 447.2 found 450.4 ([M + 3H]+, 1.5 %)


9

S-(β-amino-β-carboxyethyl)ergothioneine methyl ester sulfoxide or (2S)-N,N,N-2-

trimethylammonium-3-[2-((2R)-2-amino-2-methoxycarbonyl) ethylsulfinyl)- 1H-

imidazol-4-yl] propanoic acid (4b).


methoxycarbonyl)-ethylsulfinyl)-1H-imidazol-4-yl)] propanoic acid (4a) (45 mg, 0.10 mmol)

was dissolved in distilled H2O (1 ml) followed by the addition of trifluoroacetic acid (1 ml)

with cooling in a ice bath. The solution was allowed to stir at 0-5°C until completion (monitored

by TLC). The solvent was concentrated by lyophilisation and the residue was extracted with

DCM to remove any by product and lyophilised to dryness. The crude product was crystallized

in ethanol to afford (2S)-N,N,N-2-trimethylammonium-3-[2-((2R)-2-amino-2-

methoxycarbonyl)ethylsulfinyl)-1H-imidazol-4-yl] propanoic acid (4b) as a pale yellow and

hygroscopic crystal (25 mg; 0.07 mmol; 70 %). Mp:108-110°C; νmax (KBr)/cm-1 3409s (RNH2)

2086m (N=C-S) 1688vs (COOH) 1434s (C=C aromatic ring) 1206s (C-N) 1142s (S=O); [α]20D

= -30.26° (c = 0.39, H2O); 1H NMR (400 MHz, D2O) δ 7.38 (brs, 1H, H-5'), 4.08 (dd, J = 9.9,

4.7 Hz, 2H, H-1'' major diastereoisomer), 4.02 (dd, J = 9.6, 4.6 Hz, 2H, H-1'', minor

diastereoisomer), 3.89 (d, J = 4.2 Hz, 1H, H-2), 3.86 (s, 3H, OCH3), 3.77 (dd, J = 11.5, 4.2 Hz,

1H, H-3a ), 3.67 (dd, J = 11.05, 4.2 Hz, 1H, H-3b), 3.45 – 3.40 (m, 1H, H-2''), 3.05 (s, 9H,

NMe3); 13C NMR (101 MHz, D2O) δ 162.6 (C=O), 162.9 (C=O), 163.3 (C=O), 163.6 (C=O),

120.9 (C-2'), 118.0 (C-4'), 115.1 (C-5'), 72.2 (C-2), 66.0 (C-1'' major diastereoisomer), 62.9

(C-1'' minor diastereoisomer), 63.8 (OCH3), 43.8 (C-2''), 43.4 (NMe3), 36.5 (C-3); HRMS

(ESI+): m/z 348.1462 [M+H]+. Calculated for C13H24N4O5S+ found 348.1465 [M+H]+.


10

S1.3. 3 D ChemBioDraw Ultra 11.0 modelling of mCPBA oxidation of sulfide (3a) to

sulfoxide (4b) (milder oxidation)

Figure (S1.3) 3D possible conformation of the sulfide (3a) indicates potential face selectivity (3D ChemBioDraw

Ultra 11.0, Total energy 34.3722 Kcal/mol, Dipole/Dipole 3.0912, Steric minimise energy)

S1.4. Evidence of diastereoselectivity of sulfoxidation revealed by 1H NMR spectrum of

S-(β-amino-β-carboxyethyl)ergothioneine methyl ester sulfoxide (4b)

Figure (S1.4.1) 1H NMR spectrum of S-(β-amino-β-carboxyethyl)ergothioneine methyl ester sulfoxide (4b) in

D2O at 400 MHz from 4.15 to 3.00 ppm


11

Figure (S1.4.2) 13CNMR spectrum of S-(β-amino-β-carboxyethyl)ergothioneine methyl ester sulfoxide (4b) in

D2O at 101 MHz from 170.0 to 40.0 ppm

Figure (S1.4.3) COSY 1H – 1H NMR spectrum of S-(β-amino-β-carboxyethyl)ergothioneine methyl ester

sulfoxide (4b) in D2O at 400 MHz from 4.00 to 2.90 ppm


12

Figure (S1.4.3) HSQC 1H – 13C NMR spectrum of S-(β-amino-β-carboxyethyl)ergothioneine methyl ester

sulfoxide (4b) in D2O at 400 MHz from 4.00 to 2.90 ppm.

S-(β-amino-β-carboxyethyl)ergothioneine sulfide or (2S)-N,N,N-2-trimethylammonium-

3-[2-((2R)-2-amino-2-hydroxycarbonyl)ethylthio)-1H-imidazol-4-yl] propanoic acid

trihydrochloride salt (5a) 8

L-hercynine (100 mg, 0.50 mmol) was dissolved in distilled H2O (5 ml), followed by the

addition of concentrated HCl (37 %, 28 mg, 74 µl, 0.76 mmol). The solution was allowed to

cool in an ice bath, thereafter Br2 (104 mg, 0.65 mmol) was added drop wise, followed by the

addition of cysteine monohydrate chloride (439 mg, 2.50 mmol) 5 min later. The reaction

mixture was allowed to stir for 90 min at 0°C. Purification by Dowex chromatography (gradient

0.5-2N HCl, Dowex (50WX8-100) and reverse phase chromatography (C18) afforded (2S)-

N,N,N-2-trimethylammonium-3-[2-((2R)-2-amino-2-hydroxycarbonyl) ethylthio)-1H-

imidazol-4-yl] propanoic acid trihydrochloride salt (5a) as a pale yellow hygroscopic solid, in

trihydrochloride hydrate salt form (193 mg, 47 %). Mp: 79°C (dec), Lit. 77° C (dec)20; [α]20D

= -86.6° (c = 0.5, H2O); 1H NMR (600 MHz, D2O) δ 8.73 (d, J = 14.2 Hz, 0.5 H, H-5'), 7.41

(dd, J = 15.5, 7.8 Hz, 0.5 H, H-5'), 4.49 (dd, J = 7.9, 4.4 Hz, 1H, H-2), 4.38 (dd, J = 5.5, 4.4

Hz, 1H, H-2''), 3.49 (dd, J = 15.2, 4.4 Hz, 1H, H-1a''), 3.38 (Overlapped, s, 9H, NMe3), 3.34

(dd, J = 15.2, 7.9 Hz, 1H, H-1b''), 3.21 (dd, J = 15.2, 5.6 Hz, 1H, H-3a), 3.15 (dd, J = 15.2, 4.4


13

Hz, 1H, H-3b), 13C NMR (151 MHz, D2O) δ 171.3 (C-1), 170.9 (C-3''), 138.0 (C-2'), 129.25

(C-4'), 122.96 (C-5'), 75.29 (C-2), 55.18 (C-2''), 52.53 (NMe3), 37.07 (C-3), 24.61 (C-1'');

HRMS (ESI+): m/z 317.1284 [M]+. Calculated for C12H21N4O4S+ found 317.1277 [M]+.

(2S)-N,N,N-2-trimethylammonium-3-[2-((2R)-(tert-butoxycarbonylamino)-3-

butoxycarbonyl)ethylthio)-1H-imidazol-4-yl] benzyl propanoate (5b). 9

(2S)-N,N,N-2-trimethylammonium-3-[2-((2R)-2-amino-2-hydroxycarbonyl)ethylthio)-1H-

imidazol-4-yl] propanoic acid trihydrochloride salt (5a) (765 mg, 2.51 mmol) was dissolved in

a mixture of distilled H2O:CH3CN (1:1, 10 ml), followed by the addition portion wise of NaOH

(100 mg, 2.51 mmol). Tert-butyl dicarbonate (602 mg, 2.76 mmol) was added and the solution

was allowed to stir overnight at room temperature. The solvent was evaporated under high

vacuum to dryness, and the residue was triturated with Et2O, dried under vacuum. The crude

solid was dissolved in DMF (5ml) followed by the addition of benzyl bromide (943 mg, 5.52

mmol). The solution was allowed to stir overnight at room temperature. The solvent was

removed under high vacuum to dryness. Purification by chromatography using silica gel

column (CH2Cl2: MeOH, 70:30) afforded (2S)-N,N,N-2-trimethylammonium-3-[2-((2R)-(tert-

butoxycarbonylamino)-3-butoxycarbonyl)ethylthio)-1H-imidazol-4-yl]benzylpropanoate (5b)

as a brown gum (563 mg, 38 %). [α]20D = +0.084° (c = 6.67, MeOH), 1H NMR (400 MHz,

DMSO) δ 8.63 – 8.24 (m, 10H, 2Ph), 7.90 (s, 1H, H-5'), 4.72 (s, 2H, H-1''), 5.32 (brs, 2H, NH),

4.44 (s, 2H, H-1''''), 3.73 (d, J = 3.1 Hz, 1H, H-2), 3.66 (dd, J = 4.1, 2.7 Hz, 1H, H-2'''), 3.30

(dd, J = 11.1, 3.1 Hz, 1H, H-3a), 3.25 (dd, J = 16.8, 4.1 Hz, 1H, H-1'''a) 3.18 (dd, J = 16.8, 4.1

Hz, 1H, H-1'''b), 3.15 (dd, J = 11.1, 3.1 Hz, 1H, H-3b), 2.84 (s, 9H, NMe3), 2.68 (s, 9H, Boc);

13C NMR (101 MHz, DMSO) δ 169.4 (C=O), 169.2 (C=O), 168.7 (C=O), 138.3 (C-2'), 136.4

(C-4'), 129.7, 129.1, 128.8, 128.5, 128.0, 127.8, 127.1, 126.9 (8C, 2Ph), 125.57 (C-5'), 70.4

(C-1''), 69.5 (C-1''''), 68.0 (C(Boc)), 53.7 (C-2), 51.7 (NMe3), 51.3 (C-2'''), 37.7 (C-3), 36.3

(3C(Boc)), 25.4 (C-1'''); LRMS (EI+) m/z calculated for C25H31N4O4S+ 483.2 [M- Boc- CH3]

+

found 483.7 ([M- Boc- CH3]+, 2 %).


14

S1.5. Synthesis of hercynine and ergothioneine deuterated compounds

NHN

N

O

O

CR3

hercynine : R=H7 : R=D

(viii)

NR2HN

N

O

OH

histidine : R=H6 : R=Me

NH2HN

N

O

OHHS

mercapto-histidine (8)

(ix) (x)

crude enzyme

NHN

HN

O

OS

CR3

ESH (1) : R=HESH-d3 (10) ; R=D

NHN

N

O

OHRS

9 : R=t-But

Scheme S1. 2. 2. Synthesis and enzymatic production of hercynine-d3 (7) and ESH-d3 (10). Reagents and

conditions: (viii) a) CH2O, sodium triacetoxyborohydride / CH3CN, 18-24 hrs at rt (6), b) NH4OH, CH3I or CD3I

/ MeOH, 24 h at rt, (7); (ix) a) t-BuOH / HCl, refluxed for 3-4 hrs, S-t-butyl mercaptohistidine; b) CH2O, sodium

triacetoxyborohydride / THF, 6-8 hrs at 10 °C, (9); (x) a) NH4OH, CD3I / MeOH 24 h, rt; b) HCl, 2-

mercaptoprionic acid refluxed for 21 h (quantitative).

Deuterated hercynine or (2S)-N,N,N-2-trimethylamino-d3-3-(1H-imidazol-4-

yl)propanoic acid (7)

N

23

4'

5'HN

2'N

O

O

1'' CD3

1

1'

3'

2''

L-histidine (200 mg; 1.29 mmol) was dissolved in CH3CN (10 ml), followed by the addition in

one portion of formaldehyde (37 %; 157 mg; 145 µl; 1.93 mmol. The solution was allowed to

equilibrate to room temperature, thereafter sodium triacetoxyborohydride (615 mg; 2.90 mmol)

and acetic acid glacial (73 µl) were added at an internal temperature was maintained at 0-5°C.

The resulting solution was allowed to stir at room temperature for 18-24 h period. The reaction

was quenched with 5 ml of HCl 5 % to pH ≤ 1 and then extracted with EtOAC (5 x 20 ml), the

remaining water layer was retained for recycling. The organic layer was separated, washed

with brine, dried (anhydrous MgSO4) and filtered. The filtrate was evaporated under vacuum

to obtain crude N,N-dimethyl L-histidine (6) which was used without further purification.


15

To the crude N,N-dimethyl L-histidine (6) (374 mg; assumed to be 2.02 mmol) dissolved in

MeOH (5 ml) adjusted to pH 9-10 with a solution of concentrated ammonia (25%), followed

by the addition of methyl iodate-d3 (489 mg; 3.03 mmol). The solution was allowed to stir at

room temperature for 24 hours. The solvent was evaporated under high vacuum to dryness.

Reverse phase chromatography (C18) and recrystallization in mixture of warm EtOH/H2O

afforded deuterated hercynine (7) as a yellow solid (249 mg; 61 %); Mp: 142-145 °C (dec); 1H

NMR (400 MHz, D2O) δ 8.70 (s, 1H, H-2'), 7.45 (s, 1H, H-5'), 4.44 (d, J = 7.7 Hz, 1H, H-2),

3.74 – 3.30 (m, 8H, H-1'' H-2'' & H-3); HRMS (ESI+): m/z 201.1431 [M]+.Calculated for

C9H13D3N3O2+ found 201.1414 [M]+.

Mecaptohistidine or (2S)-2-amino-3-(2-mercapto-1H-imidazol-4-yl) propanoic acid (8) 3

The synthesis of mercaptohistidine (8) was carried out as reported by Trampota et al.3

Mercaptohistidine (8) was isolated as a white powder (2.01 g; 88 %). Mp: 206-208°C (with

decomposition) Literature 204-206°C (with decomposition)3; νmax (KBr)/cm-1 3465s + 1634s

+ 1129w (RNH2 Free) 2073s (N=C-S) 1383m (RCOO-), 1H NMR (400 MHz, D2O+DCl) δ 6.87

(s, 1H, H-5'), 4.31 (t, J = 6.6 Hz, 1H, H-2), 3.28 (dd, J = 16.1, 6.6 Hz, 1H, H-3a), 3.17 (dd, J =

16.1, 6.6 Hz, 1H, H-3b), Carboxylic acid and amine protons signals were exchanged with a

D2O. 13C NMR (101 MHz, D2O) δ 170.5 (C-1), 156.6 (C-2’), 123.3 (C-4’), 116.1 (C-5’), 51.9

(C-2), 25.4 (C-3). LRMS (EI+) m/z calculated for C6H9N3O2S 187.0 found 187.0 ([M] +; 92.7

%).


16

S1.6. Characterisation of Mercaptohistidine (8) synthesized

Figure (S1.6.1) 1H NMR spectrum of Mercaptohistidine(8) in D2O + DCl at 400 MHz

Figure (S1.6.2) 13C NMR spectrum of mercaptohistidine(8) in D2O + DCl at 101 MHz.

(2S)-3-(2-(tert-butylthio)-1H-imidazol-4-yl)-2-(dimethylamino) propanoic acid (9)

In distilled H2O (18 ml) was added (2S)-2-amino-3-(2-mercapto-1H-imidazol-4-yl) propanoic

acid (8) (2.27 g; 12.1 mmol), followed by the addition of t-butanol (2.34 g; 31.5 mmol) and

concentrated hydrochloric acid (4 ml, 37 %). The resulting mixture was heated to 85-90°C and

kept at this temperature for a 3 - 4 hr period. Subsequently, the reaction mixture was


17

concentrated by lyophilisation. The free amino acid was liberated by adjusting the pH of the

solution to 5.0 with aqueous sodium acetate, followed by lyophilisation to dryness, where after

the amino acid was extracted with warm 2-propanol. The product S-t-butyl mercaptohistidine

was obtained as a yellow crystal (1.85 g; 62.7 %). [α]20D = +14.1° (c = 0.7, H2O) lit.[α]25

D =

+13° (c = 1, H2O)3; νmax (KBr)/cm-1 3448s + 1561s + 1051w (RNH2 Free) 2237w (N=C-S)

1703m (RCOOH) 1337m (CH3) 643 (S-R), 1H NMR (400 MHz, D2O) δ 7.60 (brs, 1H, H-5’),

4.18 (t, J = 3.0 Hz, 1H, H-2), 3.39 (dd, J = 11.0, 3.0 Hz, 1H, H-3a), 3.30 (dd, J = 11.0, 3.0 Hz,

1H, H-3b), 1.44 (s, 9H, t-butyl); LRMS (EI+) m/z calculated for C10H17N3O2S 243.1 found

243.1 ([M]+; 4.2%), 199.1 ([M–CO2]+; 7.1 %), 142.0 ([M–CO2–C(CH3)3]

+; 4.2%).

In a solution of THF (19 ml) was dissolved S-t-butyl mercaptohistidine (1.57 g, 6.45 mmol)

followed by the addition of formalin (37 %, 2.04 g, 25.13 mmol) portion wise. The resulting

mixture was allowed to equilibrate to room temperature and then sodium triacetoxyborohydride

(3.76 g, 17.7 mmol) was added while the reaction temperature was maintained at 0-5°C. The

resulting suspension was allowed to stir at 10°C for 6-8 hr. The reaction mixture was cooled to

-10°C, and acidified with 2 N HCl (pH ≤1). The resulting solution was lyophilised and the

residue was mixed with a 13 ml methanol followed by filtration of the undesired inorganic

salts. The filtrate was lyophilised to yield the dihydrochloride salt. The free amine was liberated

by triturating with aqueous sodium acetate to pH 5.0 evaporated to dryness, and extraction into

2-propanol, from where it was crystallized. The product (9) was obtained as colourless crystals

(590 mg; 33.7 %). 1H NMR (300 MHz, D2O) δ 6.30 (s, 1H, H-5'), 3.45 (d, J = 10.7 Hz, 1H, H-

2), 3.08 (m, 2H, H-3), 3.01 (s, 6H, H-1'' H-2''), 1.50 (s, 9H, t-butyl).

Deuterated ergothioneine or [(2S)-N,N,N-2-trimethylamino-d3-3-(2-mercapto-1H-

imidazol-4-yl)propanoic acid (10)

5'

4'HN

HN

32

O

O

N

12'

1'

3'

S

CD31''2''

(2S)-3-(2-(tert-butylthio)-1H-imidazol-4-yl)-2-(dimethylamino)propanoic acid (9) (110 mg;

0.405 mmol) was dissolved in MeOH (3 ml) and the pH was adjusted to 8.8-9.0 with

ammonium hydroxide, followed by the addition of iodomethane deuterated (70 mg, 0.61 mmol)

and the solution was allowed to stir at room temperature for 24 h. The mixture was concentrated

under vacuum and the resulting white solid (ammonium chloride) was filtered and the cake


18

was washed with methanol. The combined filtrates were evaporated to dryness to afford a

crude, deuterated S-(tert-butyl) ergothioneine. In the presence of 2-mercaptopropionic acid

(1.70 g; 16.1 mmol), crude deuterated S-(tert-butyl) ergothioneine was dissolved in 2 ml H2O

followed by the addition of HCl (1 ml, 32%). The resulting mixture was refluxed for 21 hours.

After cooling the reaction mixture was extracted with EtOAc (3 x 15 ml) and then the aqueous

layer was adjusted to pH 7 with a solution of ammonia (25 % v/v) followed by lyophilisation.

The residue was again extracted with ethyl acetate (3 x 20 ml) followed by partitioning in a

mixture of distilled water: ethyl acetate 50:50 (v/v). The aqueous layer was retained and the

organic phase discarded. The aqueous phase was lyophilised to dryness. Purification by reverse

chromatography (C18) and recrystallization afforded the product (10) as a yellow solid (93 mg;

quantitative). Mp:158-160 °C (dec); 1H NMR (400 MHz, D2O) δ 6.95 (s, 1H, H-5'), 4.34 – 4.13

(m, 1H, H-2), 3.73 – 3.43 (m, 6H, H-1'' H-2''), 3.41 (dd, J = 11.3, 8.5 Hz, 2H, H-3); 13C NMR

(101 MHz, D2O)δ 180.3 (C-1), 134.9 (C-2'), 119.1 (C-4'), 115.8 (C-5'), 75.5 (C-2), 52.5 (C-1''

C-2'' C-3''), 22.7 (C-3); HRMS (ESI+): m/z 233.1152 [M]+. Calculated for C9H13D3N3O2S+,

found 233.1161 [M]+.

S1.7. 1H NMR of ergothioneine-d3 (10) synthesized

Figure (S1.7.1) 1HNMR of ergothioneine-d3 (10) in D2O at 400 MHz

S1.8. Synthesis of Ergothioneine substrates and inhibitor


19

NHBocN

N

O

OH

NH2N

N

O

OH

NN

N

O

OH

NH2

HS

O

OH

cysteine

NHN

N

O

OSHO

NH2

O

Quantitative

TFA

DCM

Crude yield= 93%

CH2O, NaBH(OAc)3

MeI / THF

1. NBS (2.5 eq)/ DMFdark

Isolated yield= 76 %2.

11 1312

(2.5 eq)

15

NN

N

O

O

14

Quantitative

CH3CN

NHN

N

O

OSHO

NH2

O

NHN

N

O

OSHO

NH2

O

O

O O

II

III

p-TSOH (Cat)

H2O2 (2.4 eq)

Isolated yield= 71 %

Isolated yield= 65 %

Boric acid (Cat)

H2O2 (4.8 eq)

Scheme S8. Synthesis of sulfoxide (II) and sulfone (III).

N-benzyl-L-histidine (12)

In dichloromethane (10 mL) was suspended 11 (750 mg, 2.17 mmol) followed by the addition

of trifluoroacetic acid (1 mL) with cooling in an ice bath. The resulting homogenous solution

was allowed to stir at room temperature until complete deprotection as showed by thin layer

chromatography. Solvent was removed and triturated with Et2O (15 mL) and dried to afford

the TFA salt product 12 as white crystal (700 mg, 90 %). Mp: 230-233 °C, (Lit. 240 °C)10; 1H

NMR (400 MHz, DMSO) δ 9.01 (s, 1H, H-2'), 7.50 (s, 1H, H-5'), 7.39 (m, 5H, Phenyl), 5.37

(s, 2H, H-1''), 4.22 (t, J = 7.0 Hz, 1H, H-2), 3.22 (dd, J = 15.6, 7.0 Hz, 1H, H-3a), 3.14 (dd, J

= 15.6, 7.0 Hz, 1H, H-3b); 13C NMR (101 MHz, DMSO) δ 170.1 (C-1), 136.3 (C-2''), 135.8

(C-2'), 130.0 (C-4'), 129.4 (C-5'' C-6''), 129.0 (C-7''), 128.6 (C-3''C-4''), 120.6 (C-5'), 51.7 (C-

1''), 51.6 (C-2), 26.3 (C-3).


20

Figure S1. 8. 1. 1H NMR spectrum of (12) in DMSO at 400 MHz.

Figure S1. 8. 2. 13 C NMR spectrum of (12) in DMSO at 101 MHz.


21

(S)-3-(1-benzyl-1H-imidazol-4-yl)-2-(dimethylamino)propanoic acid (13)

NN

N

O

OH1

1'

3'

1''2''

3''

4''

5''

6''

7''2

3

5'2'

4'

2'''1''''

In CH3CN (20 mL) was suspended 12 (1.30 g, 5.30 mmol) followed by the addition of

formaldehyde (1.2 mL, 15.5 mmol, 37 %). To the resulting homogenous solution was added

NaBH(OAc)3 (3.2 g, 15.5 mmol) and the solution was allowed to stir at room temperature for

24 hours. Undesirable salts were filtered thought celite and the solvent evaporated to dryness

to afford the crude dimethyl product 13 as yellow oil (1.44 g, quantitative). Reverse C18

column chromatography afforded a product as a colourless solid (1.4 g, quantitative). Mp: 70-

73 °C (dec); 1H NMR (300 MHz, D2O) δ 8.73 (s, 1H, H-2'), 7.51 – 7.37 (m, 5H, Ph), 7.34 (m,

1H, H-5'), 5.35 (s, 2H, H-1''), 4.31 (dd, J = 9.5, 4.7 Hz, 1H, H-2), 3.48 (dd, J = 15.4, 4.7 Hz,

1H, H-3a), 3.39 (dd, J = 15.4, 9.5 Hz, 1H, H-3b), 2.96 (s, 6H, H-1''' H-2'''); 13C NMR (101

MHz, D2O) δ 168.7 (C-1), 135.2 (C-2'), 135.1 (C-2''), 133.6 (C-4'), 129.4 (C-3'' C-4''), 128.5

(C-5'' C-6''), 127.6 (C-7''), 121.0 (C-5'), 66.0 (C-2), 65.9 (C-1''), 52.9 (C-1''' C-2'''), 21.9 (C-3);

LRMS (EI+) m/z calculated for C15H19N3O2 273.1 [M]+ found 273.1 ([M]+, 7 %), calculated for

C14H19N3 229.2 [M-CO2]+ found 229.1 ([M-CO2]

+, 58 %), calculated for C12H13N2 [M-H-CO2

-N(CH3)2]+ 185.1 found 185.1 ([M-H-CO2 –N(CH3)2]

+, 69 %).

NN

N

O

OH1

1'

3'

1''2''

3''

4''

5''

6''

7''2

3

5'2'

4'

2''' 1''''

2.53.03.54.04.55.05.56.06.57.07.58.08.59.0f1 (ppm)

-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000

26000

28000

30000

32000

34000

36000Hist NCbz NMe2/1582

KH00360097 in D2O

2.9

6

3.3

53.3

8

3.4

03.4

3

3.4

53.4

7

3.5

03.5

2

4.2

9

4.3

04.3

2

4.3

4

4.7

9 H

DO

5.3

5

8.7

3

H-2'

Ph

H-5'

H-1''

HDO

H-2 H-3

H-1''' & 2'''

Figure S1. 8. 3. 1 H NMR spectrum of (13) in D2O at 300 MHz.


22

NN

N

O

OH1

1'

3'

1''2''

3''

4''

5''

6''

7''2

3

5'2'

4'

2''' 1''''

102030405060708090100110120130140150160170f1 (ppm)

-1000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

1400013C NMR/1581

KH00360096 in D2O13C SpectrumKhonde

21.9

1

52.8

9

65.9

1

65.9

6

120.9

7

127.6

3

128.4

9129.3

7

133.5

9135.0

5

135.2

0

168.7

2

C-1

C-2 & C-1''

C-1''' & C-2'''

C-3C-5'

C-2'

C-4'

Ph

Figure S1. 8. 4. 13 C NMR spectrum of (13) in D2O at 101 MHz.

(2S)-N,N,N-2-trimethylethanaminium-3-(1-benzyl-1H-imidazol-4-yl)propanoic acid (14)

In dry tetrahydrofuran (10 mL) was dissolved the crude dimethyl product 13 (200 mg, 0.732

mmol) followed by the addition of MeI (50 µL, 125 mg, 0.878 mmol). The resulting solution

was allowed to stir at room temperature in the dark for 1-2 days. The solvent was removed to

afford the product 14 as a yellow oil (197 mg, 93 %). Crystallization in the absolute ethanol

afforded product 14 as yellow solid. Mp: 90-93 °C; 1H NMR (300 MHz, D2O) δ 8.32 (s, 1H,

H-2'), 7.63 – 7.34 (m, 5H, Ph), 7.25 (s, 1H, H-5'), 5.34 (s, 2H, H-1''), 3.99 – 3.87 (m, 1H, H-

2), 3.50 – 3.20 (m, 2H, H-3), 3.33 (s, 9H, H-1'''H-2'''H-3'''); 13C NMR (101 MHz, D2O) δ 170.4

(C-1), 137.1 (C-2'), 135.7 (C-2''), 132.0 (C-4'), 129.2 (C-3''C-4''), 128.7 (C-5''C-6''), 128.0 (C-

7''), 119.4 (C-5'), 78.0 (C-2), 52.3 (C-1''' C-2''' C-3'''), 51.4 (C-1''), 24.8 (C-3); LRMS (EI+) m/z

calculated for C16H22N3O2+ 288.2 [M]+ found 288.2 ([M]+, 11 %), calculated for C15H22N3

+

244.2 [M-CO2 and -H]+ found 244.1 ([M-CO2 and -H]+, 64 %), calculated for C14H18N3+ 228.2

NN

N

O

O1

1'

3'

1''2''

3''

4''

5''

6''

7''2

3

5'2'

4'

2'''

1''''3''''


23

[M-CO2 –H – CH3]+ found 228.1 ([M-CO2 –H – CH3]

+, 100 %), calculated for C12H13N2+ 185.1

[M-CO2 –2H –N(CH3)3]+ found 185.1 ([M-CO2 –2H – N(CH3)3]

+, 62 %).


NN

N

O

O1

1'

3'

1''2''

3''

4''

5''

6''

7''2

3

5'2'

4'

2'''

1''''3''''

102030405060708090100110120130140150160170f1 (ppm)

-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000

26000

C13 NMR/2981

KH00360099 in D2O13C SpectrumKhonde

24.7

9

51.4

1

52.2

9

78.0

1

119.4

1

127.9

8128.6

9

129.2

4132.0

0

135.7

0137.0

5

170.3

8

C-1

C-3

C-1''

C-1''' 2''' 3'''

C-2C-5'

C-4'

C-2'

C-2''

Ph

Figure S1. 8. 6. 13 C NMR spectrum of (14) in D2O at 101 MHz.

NN

N

O

O1

1'

3'

1''2''

3''

4''

5''

6''

7''2

3

5'2'

4'

2'''

1''''3''''

2.83.03.23.43.63.84.04.24.44.64.85.05.25.45.65.86.06.26.46.66.87.07.27.47.67.88.08.28.4f1 (ppm)

-5000

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

60000

65000C18 column/2181

KH00360098C in D2O

3.3

3

4.7

9 H

DO

5.3

4

7.2

5

8.3

0

Ph

H-2' H-5'

H-1''

HDO

H-2

H-1''' 2''' & 3'''

H-3


24

S1.9. Selective and mild bromination of the imidazole ring

Scheme S1.9. 1. Selective and mild bromination of the imidazole ring.

The bromination conditions were optimised to be very selective. Two brominated intermediates

have been found stable enough to be isolated by reverse phase C18 chromatography. The mono

brominated intermediate, 5-bromo hercynine (A) was isolated in very high yield (90 %), while

the 2, -5 dibromo hercynine intermediate (B) was isolated in a low yield of 10 %.

Figure S1. 9. 1. 1 H NMR spectrum of (A) in D2O at 300 MHz.


25

2.22.42.62.83.03.23.43.63.84.04.24.44.64.85.05.25.45.65.86.06.26.46.66.87.07.27.47.67.88.08.2f1 (ppm)

-500

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500KH00360072B_1H_D2O

LM20_1h

N(CH3)3HN

N

O

O1

1'

3'2

3

5'

2' 4'Br

Br

H-2H-3

-(CH3)3

Figure S1. 9. 2. 1 H NMR spectrum of (B) in D2O at 300 MHz.

S1.10. Hercynyl cysteine thioether (15) (One pot synthesis)

In dimethylformamide (8 mL) was dissolved 14 (595 mg, 2.43 mmol) followed by the addition

of N-bromosuccimide (1.8 g, 6.08 mmol). The resulting solution was allowed to stir at room

temperature until complete disappearance of the starting material (thin layer chromatography

monitoring), the solution became red-orange indicating the successful bromination.

After successful bromination, cysteine HCl. H2O (1.07 g, 6.08 mmol) was added in one portion

and the resulting solution was allowed to stir at room temperature for 24 hours. Reverse phase

chromatography C18 afforded the product 15 isolated as the yellow hygroscopic solid acetate

salt form (695 mg, 76 %). 1H NMR (400 MHz, D2O) δ 7.41 (m, 1H), 4.54 (dd, J = 7.7, 4.4 Hz,

1H, H-2''), 4.42 (t, J = 5.0 Hz, 1H, H-2), 3.50 (dd, J = 15.2, 4.4 Hz, 1H, H-3a''), 3.36 (dd, J =

15.2, 7.7 Hz, 1H, H-3b''), 3.19 (m, 2H, H-3), 2.80 (s, 9H, H-1''H-2''H-3''), 2.75 (s, 3H, acetate);

13C NMR (101 MHz, D2O) δ 170.3 (C-1''), 170.0 (C-1), 129.4 (C-2'), 128.9 (C-4'), 120.9 (C-

5'), 61.0 (C-2), 54.4 (C-2''), 51.7 (C-1'''C-2'''C-3'''), 36.3 (C-3''), 23.9 (C-3); HRMS (ESI+): m/z

317.1284 [M]+. Calculated for C12H21N4O4S+ found 317.1277 [M]+.


26


S1.11. Synthesis of hercynyl cysteine sulfoxide (I) and sulfone (II).

S.11.1. S-(β-amino-β-carboxyethyl)ergothioneine sulfoxide or (2S)-N,N,N-2-

trimethylammonium-3-[2-((2R)-2-amino-2-hydroxycarbonyl) ethylsulfinyl)- 1H-

imidazol-4-yl] propanoic acid (II) 11

To a solution of H2O2 (30 %, 224 mg, 6.58 mmol, 2.4 eq) were added 15 (870 mg, 2.32 mmol)

and para toluene sulfonic acid (15 mg, 0.08 mmol). The resulting reaction mixture was allowed

to stir at room temperature for 24 hours. At the end the reaction was quenched by the addition

of H2O (10 mL) and evaporated under high vacuum to afford crude product, which was purified

by C18 reverse phase to afford product II as a yellow solid (640 mg, 71 %). 1H NMR (300

MHz, D2O) δ 8.01 (s, 1H, H-5'), 4.49 (dd, J = 8.6, 3.3 Hz, 1H, H-2''), 3.90 (dd, J = 16.1, 9.3

Hz, 1H, H-2), 3.65 (dd, J = 15.0, 3.3 Hz, 2H, H-1''), 3.52 (dd, J = 9.3, 4.9 Hz, 1H, H-3a), 3.44

(dd, J = 9.3, 4.9 Hz, 1H, H-3b), 2.86 (s, 9H, NMe3), 2.79 (s, 3H, acetate); 13C NMR (101 MHz,

D2O) δ 171.8 (C-3''), 170.1 (C-1), 156.6 (C-2'), 129.5 (C-4'), 125.5 (C-5'), 72.5 (C-2), 49.5


27

(NMe3), 49.1 (C-1''), 43.5 (C-2''), 20.8 (C-3); HRMS (ESI+): m/z 334.1306 [MH]+. Calculated

for C12H22N4O5S2+, found 334.1321 [MH]+.

Figure S1. 11. 1. 1 H NMR spectrum of (I) in D2O at 300 MHz.

S1.11.2. S-(β-amino-β-carboxyethyl)ergothioneine sulfone or (2S)-N,N,N-2-

trimethylammonium-3-[2-((2R)-2-amino-2-hydroxycarbonyl) ethylsulfonyl)- 1H-

imidazol-4-yl] propanoic acid (III)12

15 (810 mg, 2.07 mmol) was added to a solution of H2O2 (30 %, 416 mg, 12.24 mmol, 4.8 eq)

and boric acid (5 mg, 0.08 mmol), and the reaction mixture was allowed to stir at room

temperature for 24 hours. At the end the reaction was quenched by the addition of H2O (10

mL) and evaporated under high vacuum to afford crude product, which was purified by C18

reverse phase to afford product III as a yellow solid (545 mg, 65 %). 1H NMR (300 MHz, D2O)

δ 8.01 (s, 1H, H-5'), 4.52 (dd, J = 8.3, 3.1 Hz, 1H, H-2''), 3.89 (dd, J = 16.1, 9.3 Hz, 1H, H-2),

3.65 (dd, J = 15.0, 2.8 Hz, 2H, H-1''), 3.59 – 3.43 (m, 2H. H-3), 2.85 (s, 9H, NMe3), 2.79 (s,

3H, acetate); 13C NMR (101 MHz, D2O) δ 171.7 (C-3''), 170.0 (C-1), 159.8 (C-2'), 156.6 (C-


28

4'), 132.9 (C-5'), 64.3 (C-2), 56.7 (C-1''), 49.4 (NMe3), 49.1 (C-2''), 34.7 (C-3); HRMS (ESI+):

m/z 349.1177 [M]+. Calculated for C12H21N4O6S+, found 349.1192 [M]+.

Figure S1. 11. 2. 1 H NMR spectrum of (II) in D2O at 300 MHz.

S2. Total Protein extraction and Purification from Mycobacterium

smegmatis.

S2.1. Mc2155 (M. smegmatis) growth conditions.

M. smeg culture (800 ml) were grown to exponential phase, and then dried to obtain 10 g of

dry cells. The obtained pellets of M. smeg cells were thereafter stored at -80°C until it was

required.

S2.2.Total protein extraction.

M.smeg cells was sonicated for 35minutes at 4°C (25 pulsars), followed by the addition of

potassium phosphate buffer (60 ml; pH 7). The solution was allowed to stir at 4°C for 10

minutes and thereafter centrifuged at 3000 rpm for 20 min. The supernatant was collected,

measured and then the appropriate amount of ammonium sulphate gradually added while

stirring at 4 °C overnight to obtain 60-70 % saturation. 13


29

After precipitation of total protein the suspension was centrifuged at 4°C at 3000 rpm for 20

min and stored at -20°C.

S2.3. Total protein purification.

The complex total protein ammonium salts precipitate was resuspended in buffer mixture (20

ml; pH 7) containing pyridoxal phosphate (10 ml; 20µM), potassium phosphate buffer (8 ml;

50 mM; pH 7) and (2 ml; 1mM EDTA).

S2.4. Protein calibration curve

In order to determine the total protein concentration the protein Dc assay and the Bradford

assays were used, here we report the Bradford calibration curve which was found to be more

accurate than the protein Dc in our case.

Figure (S2.4) Bradford protein concentration calibration curve.

The calculated M. smeg total protein concentration was found to be 10.33 µg/µl

S3. HPLC –ESI/MS (QTOF) analysis.

S3.1. Materials and methods

Analyses were carried out with a UHPLC Agilent 1290 Infinity Series (Germany), accurate

mass spectrometer Agilent 6530 Qradrupole Time Of Flight (QTOF) equipped with an Agilent

jet stream ionization source (positive ionization mode) (ESI+) and column (Polaris 3 C18 Ether

100 X 2 mm, particle size 3 µm, Agilent, Germany).

15 µL of concentrate samples were injected into the LCMS. Analyte separation was attempted

in 0.1 % formic acid in milli-Q water (solvent A) and mixture of 90 % acetonitrile, 0.1 %


30

formic acid, 10 % milli-Q water (solvent B) as mobile phase in an isocratic flow rate of 0.3

mL/min.

The system was controlled with the software packages Mass Hunter workstation software

(Qualitative and Quantitative version B.05.00; Build 5.0.519.0, Agilent 2011, Germany)

S3.2. Experimental LCMS

Due to the polarity and charge on the quaternary ammonium group present in all metabolites,

poor retention on the UHPLC (Eclipse + C18 RRHD 1.8 µm.2.1 X 50) column was observed

for ESH (RT= 0.8 min). All later analysis were performed with an improved column as

described in the section S3.1 (RT = 1.5 min)

6x10

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

3.8

4

4.2

4.4

4.6

4.8

5

+ESI TIC Scan Frag=175.0V Zac_31Oct_Test_HD_500ng_1.d

4x10

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

+ESI EIC(201.1414) Scan Frag=175.0V Zac_31Oct_Test_HD_500ng_1.d

* 27.9

Counts vs. Acquisition Time (sec)

16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74

NHN

N

O

O

CD3

4x10

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

+ESI Scan (27.9 sec) Frag=175.0V Zac_31Oct_Std_HD_500ng_1.d

202.1454

201.1414

198.8621196.8645

203.1468

Counts vs. Mass-to-Charge (m/z)

196 197 198 199 200 201 202 203 204 205 206

[Md3]+

[Md3+H]+

NNH

N

O

O

CD3

(7)

Figure (S3.2.1) TIC and ESI/QTOF mass spectra of Hercynine-d3 (7) in positive ion mode


31

2x10

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1+ESI EIC(233.1160) Scan Frag=175.0V Zac_31Oct_Std_ED1_500ng_1.d

* 0.795

1

Counts (%) vs. Acquisition Time (min)

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2

O

O

NHN

HNS

CD3

(10)

4x10

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

3.8

4

4.2

+ESI Scan (0.795 min) Frag=175.0V Zac_31Oct_Std_ED1_500ng_1.d

194.1189

233.1160

131.9315 141.9600224.1299

173.0797

158.0043

189.1261 217.1053

182.9028208.1348


125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235

O

O

NHN

HNS

CD3

[Md3]+

[Md3 - CO2]+

Figure (S3.2.2) TIC and ESI/QTOF mass spectra of Ergothioneine-d3 (10) in positive ion mode


32

6x10

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

+ESI TIC Scan Frag=175.0V Khonde_Nov5_Std_MS.d

5x10

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

+ESI EIC(349.1832) Scan Frag=175.0V Khonde_Nov5_Std_MS.d

* 180.8


20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240

NHN

N

O

OS

H2N

MeO2CO

Figure (S3.2.3) ESI/QTOF mass spectra of S-(β-amino-β-carboxyethyl)ergothioneine methyl ester sulfoxide

(4b) in positive ion mode.

7x10

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

+ESI TIC Scan Frag=175.0V Zac_31Oct_Test_SL_500ng_1.d

4x10

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

2.4

+ESI EIC(317.1277) Scan Frag=175.0V Zac_31Oct_Std_SL_500ng_1.d

* 31.6


20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230

CO2

NHN

NS

H2N

HO2C

15


33

4x10

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

1.3

1.35

1.4

+ESI Scan (31.6 sec) Frag=175.0V Zac_31Oct_Std_SL_500ng_1.d

317.1277

303.1484


303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323

[M-CH3]+

[M]+

[M+H]+

CO2

NHN

NS

H2N

HO2C

(15)

Figure (S3.2.4) TIC and ESI/QTOF mass spectra of S-(β-amino-β-carboxyethyl)ergothioneine sulfide (15) in

positive ion mode

2x10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1+ESI TIC Scan Frag=175.0V Khonde_June3_2013_KH05_run3.d

2x10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1+ESI EIC(335.1384) Scan Frag=175.0V Khonde_June3_2013_KH05_run3.d

* 0.680


0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65 1.7 1.75 1.8 1.85 1.9 1.95 2 2.05 2.1 2.15 2.2

NHN

N

O

OSHO

NH2

O

O

(II)

4x10

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

+ESI Scan (0.697 min) Frag=175.0V Khonde_June3_2013_KH05_run3.d

332.1457


332 332.25 332.5 332.75 333 333.25 333.5 333.75 334 334.25 334.5 334.75 335 335.25 335.5

333.1381

335.1384

334.1321

[M+2H]+

[M+2H]+

[M+2H]+

NHN

N

O

OSHO

NH2

O

O

(II)

Figure (S3.2.5) TIC and ESI/QTOF mass spectra of S-(β-amino-β-carboxyethyl)ergothioneine sulfoxide (II)

in positive ion mode.


34

4x10

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

2.1

2.2

2.3

2.4

2.5

+ESI Scan (37.6 sec) Frag=175.0V Zac_31Oct_Std_SO_500ng_2.d

349.1177

Counts vs. Mass-to-Charge (m/ z)

346.75 347 347.25 347.5 347.75 348 348.25 348.5 348.75 349 349.25 349.5 349.75 350 350.25

NHN

N

O

OSHO

NH2

O

O O

[M]+

[M+H]+

(III)

Figure (S3.2.6) TIC and ESI/QTOF mass spectra of S-(β-amino-β-carboxyethyl)ergothioneine sulfone (III) in

positive ion mode

S4. In vitro reconstituted biosynthesis of ergothioneine in Mycobacteria

smegmatis. 14

The experiments were performed in triplicate, repeated several times (more than three times)

and these results were reproducible.

7x10

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

+ESI TIC Scan Frag=175.0V Zac_31Oct_Std_SO_500ng_2.d

4x10

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

3.2

+ESI EIC(349.1182) Scan Frag=175.0V Zac_31Oct_Std_SO_500ng_2.d

* 37.6


15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

NHN

N

O

OSHO

NH2

O

O O


35

S4.1. ESH Calibration curve

In order to establish a calibration curve for the quantification of ESH, eight different

concentrations (0.78, 1.56, 3.125, 6.25, 12.5, 25, 50, 100 ng/ml) of ESH were prepared in

triplicate, giving a limit of quantification (LOQ) 0.78 ng/ml for ESH which was similar to the

one found by L-Z Wang et al.15 The limit of detection (LOD) for ESH was 9 pg/ mL. The

retention time for ESH was 1.5 minute. Excellent symmetric peaks were achieved for both ESH

standard and reactions samples analysed.

Figure (S4.1.1) Calibration curve of ESH.

Figure (S4.1.2) Overlaid TIC of Ergothioneine. Retention time of 1.5 min

4x10

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

+ESI Scan (1.473 min) Frag=120.0V EGQuant_Dec18_2013EGStandarda4.d

224.1273

222.1117

230.0967

217.0688

214.9165

233.0404


212 214 216 218 220 222 224 226 228 230 232 234 236 238 240 242 244 246 248

O

O

NHN

HNS

[M]+

[M+H]+


36

Figure (S4.1.3) ESI/QTOF mass spectra of ESH standard in positive ion mode

S4.2. Enzymatic synthesis of ergothioneine-d3 (10) using Hercynine-d3 (7) as a substrate.

One set of 100 µl reactions (1) containing 20 mM Tris HCl pH= 7.4, 20 mM NaCl , 0.2 Mm

FeSO4.7 H2O, 0.5 mM mercaptoethanol, 83 µl of crude enzymes and 50 mM of either (1) S-

hercynine-d3 (7). The crude enzyme reactions were incubated for 1 day at 37° C. The reaction

was stopped by heating the mixture at 90°C for 2 min followed by lyophilisation and

subsequent reconstitution in LC buffer before analysis by LC/MS.

Figure (S4.2.1). LCMS spectrum of ESH-d3 in-vitro reconstititued experiment using hercynine-d3 (7) as

substrate.

S4.3. Biotransformation of substrates to ergothioneine using crude M. smegmatis enzymes

preparation

Three sets of 100 µl reactions (1- 4) containing 20 mM Tris HCl pH= 7.4, 20 mM NaCl , 0.2

Mm FeSO4.7 H2O, 0.5 mM mercaptoethanol, 83 µl of crude enzymes and 50 mM of either (1)

S-(β-amino-β-carboxyethyl)ergothioneine sulfide (15) (2) S-(β-amino-β-


37

carboxyethyl)ergothioneine sulfoxide (II) (3) S-(β-amino-β-carboxyethyl)ergothioneine

sulfone (III) or (4) control (only crude enzymes no substrates). The crude enzyme reactions

were incubated for 1 day at 37° C. The reaction was stopped by heating the mixture at 90°C

for 2 min followed by lyophilisation and subsequent reconstitution in LC buffer before analysis

by LC/MS.

Figure (S4.3.1). TIC extracted for ESH in-vitro reconstititued experiment using substrate: (a) S-(β-amino-β-

carboxyethyl)ergothioneine sulfide (15) as substrate, (b) S-(β-amino-β-carboxyethyl)ergothioneine sulfoxide (II)

as substrate and (c) S-(β-amino-β-carboxyethyl)ergothioneine sulfone (III) as substrate

S4.4. Non enzymatic cleavage of C-S bond catalysed by PLP

Three sets of 100 µl reactions (1-3) containing 20 mM Tris HCl pH= 7.4, and 50 mM of either

(1) S-(β-amino-β-carboxyethyl)ergothioneine sulfide (15) and PLP (2) S-(β-amino-β-

carboxyethyl)ergothioneine sulfoxide (II) and PLP or (3) S-(β-amino-β-

carboxyethyl)ergothioneine sulfone (III) and PLP. The non-enzymatic reactions were

incubated for 1 day at 37° C, followed by lyophilisation and subsequent reconstitution in LC

buffer before analysis by LC/MS.

1x10

0

0.2

0.4

0.6

0.8

1

+ESI EIC(230.0958) Scan Frag=120.0V EGJan4-r002.d

* 1.493

2x10

0

0.2

0.4

0.6

0.8

1

+ESI EIC(230.0958) Scan Frag=120.0V EGJan7-r001.d

* 1.481

1x10

0

2

4

6

8

+ESI EIC(230.0958) Scan Frag=120.0V EGQuant_Dec18_201310x.d

* 1.487


0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9

NHN

N

O

OS

CO2H

H2N

O

O

(III)

NHN

N

O

OS

CO2H

H2N

O

(II)

NHN

N

O

OS

CO2H

H2N

(15)

a)

b)

c)

ESH

ESH

ESH


38

Figure (S4.5.1). Non enzymatic production of ESH catalysed by PLP. TIC extracted for ESH and PLP using S-

(β-amino-β-carboxyethyl)ergothioneine sulfide (15), S-(β-amino-β-carboxyethyl)ergothioneine sulfoxide (II) and

S-(β-amino-β-carboxyethyl)ergothioneine sulfone (III). Only S-(β-amino-β-carboxyethyl)ergothioneine sulfide

(15) produced significant amount of ESH (96.34 ng/ mL) while sulfoxide (II) and sulfone (III) did not produce

ESH at all.

Figure (S4.5.2) Non enzymatic production of ESH graph contain; 100 µl reactions containing 20 mM Tris HCl

pH= 7.4, 20 mM NaCl, 50 mM of either (1) sulfide (15) plus PLP, (2) sulfoxide (II) plus PLP, (3) sulfone (III)

plus PLP respectively. Reaction time: 24 h.

2x10

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1+ESI EIC(230.0950) Scan Frag=120.0V EGQuant_Dec18_201305x.d


0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7

NHN

N

O

OS

COOH

H2N

(15)

PLP

ESH


39

S5. Proposed mechanism of reaction of C-S of sulfide (15), sulfoxide (II)

and sulfone (III) catalysed by PLP.

S5.1 β-Elimination of the sulfoxide (II)

S5.2 Sulfenic acid conversion to ESH


40

S5.3 β-Elimination of the sulfide (15)

S6. References


41

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and silicon, 2013, 188, 833-838

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Supporting information Improved synthesis of the super